The present disclosure relates to a sprayer arrangement for a coating machine for the serial electrostatic coating of workpieces, such as vehicle bodies or parts thereof for example. The sprayer arrangement may in particular include an electrostatic sprayer and the front arm (arm 2) of a coating robot, on which the sprayer is arranged via the customary wrist joint.
Electrostatic sprayers are generally known. In the case of rotary sprayers they contain, in addition to a turbine (i.e. a pneumatic or hydraulic drive) or an electric motor for driving the sprayer head, various components such as e.g. valves, valve terminals, bus connection modules for field bus systems, valve control systems, drive control loops and other controllers of any type, inductive, optical and/or capacitive sensors, high-voltage generators, etc.
In sprayers which operate with direct charging of the coating material, usually the entire sprayer is placed at high voltage so that the coating material is charged by an electrode device containing all the electrically conductive parts with which it comes into contact, such as the sprayer head, paint pipe, screw connections, etc. Alternatively, an external charging of the coating material by means of external electrodes is possible.
An electrostatic rotary sprayer which contains an electric motor controlled by a safety transformer is disclosed in WO 2005/110613. Further information regarding electrostatic sprayers and the components thereof can be found for example in EP 0 219409, EP 1 245291, EP 1 293308 and EP 1 394757.
EP 1 232 799 describes an air-operated sprayer comprising components which can easily be separated from and connected to one another, at the points of separation of which there is a need for just as easily releasable and connectable electric line connections. Instead of the plug-in contacts used previously for this, the line connections in this air-operated sprayer include inductive couplers with, in each case, two flat coils in particular of the pot core type, which are said to be so small that practically no structural modifications are required on the separable parts of the sprayer which can instead be connected by means of plug-in connections.
DE 103 09 143 describes supplying scraper sensors (pig sensors) on a high-voltage scraped paint conveying line with the voltage they require via an isolating transformer, and to transmit the sensor signals from the high-voltage area to an external evaluation circuit via optocouplers.
The use of the high voltage during application generally requires large isolation distances between the components which are at high voltage and those at low potential, some of which may also be located in the arm of a robot serving as the coating machine. However, the space conditions in the sprayer arrangement often do not allow any separation between components at high voltage and components which are at ground or low potential. Consequently, a complete charging of the components in the sprayer arrangement may be necessary.
An electrostatic sprayer contains various components which have to be supplied with electrical power and/or have to receive and/or transmit electrical signals. All the actuators and sensors and other electronic components of the sprayer require an electrical power supply, and all the actuators provided therein require signals coming from outside, while all the sensors and other electronic components deliver, for example, diagnostic data and other signals to the outside, in particular including actual values of externally controlled parameters of the sprayer.